StoreFront tracks inventory on the product level. This means that you can set the product quantity for each product separately. A product's quantity is automatically reduced when this product is bought. When a product's quantity is decreased to 0, the product gets Out of stock status and can't be ordered anymore.
What happens when my product goes out of stock?
When a product becomes Out of stock the StoreFront store administrator will be notified.
Product quantity can be set in the StoreFront control panel (→ Catalog → Products → Product modify page → Stock Control block → Click Manage link).
Select the Unlimited option and the product's quantity will never be decreased to 0 and, thus, will never be sold out. Unlimited quantity functionality usually is used for virtual products or services.
If you set product quantity, it will be automatically reduced after each purchase until it reaches zero. After that the product status will change to Out of stock and will not be available for sale. You can hide the Out of stock products in your store using Hide out of stock products option in the StoreFront control panel → System settings → General → Cart. If you would like these products to be shown in your store, but not available for sale, you should switch this option off. You can easily get the list of the Out of stock products using the special Availability filter. Go to StoreFront control panel → Catalog → Products page and choose Enabled , but out of stock.
Can I get notifications when my product stock gets low?
Sometimes you need to get notified when the stock is low, but has not reached zero yet. In order to set the value that will be treated as low you should use the Send me a note when quantity reaches input box. Just enter the desired quantity there.
If you want to track the inventory of each option selection (e.g. one t-shirt is available in different colors and you have 2 white, 3 black and 1 blue), you should use product combinations.
Low stock and Out of stock notifications are sent to the email specified in the StoreFront control panel → Settings → Mail → Scroll down to Admin Notifications → Make sure that Low Stock Notification is enabled.